In cases where compression is in use, putting the waitpid() for the
decompression tool before the qemudWaitForMonitor() call appears to
eliminate the race in question.

As much of a cheap hack as it is, it seems like it would resolve the
race condition in question to always spawn and block on an intermediate
process, even if this means having *two* "cat" processes between
libvirtd and the qemu or kvm it is starting.